pinctrl: uniphier: fix USB3 pin assignment for Pro4

According to pinctrl assignment for Pro4, each definition of USB#2 and
USB#3 are as follows.

  184: USB2VBUS
  185: USB2OD
  186: USB2ID
  187: USB3VBUS
  188: USB3OD

USB#2 has an additional pin "USB2ID", but the chip doesn't use this pin
while in host-mode. Considering this pin, the pin definitions for USB#3
should be {187, 188}.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>